Biomedical subjects

S Korrick

Publications and source records attributed to S Korrick.

5 recordsLinked to original sources

PubMed2001

Influence of bone resorption on the mobilization of lead from bone among middle-aged and elderly men: the Normative Aging Study.

Bone stores of lead accrued from environmental exposures and found in most of the general population have recently been linked to the development of hypertension, cognitive decrements, and adverse reproductive outcomes. The skeleton is the major endogenous source of lead in circulating blood, particularly under conditions of accelerated bone turnover and mineral loss, such as during pregnancy and in postmenopausal osteoporosis. We studied the influence of bone resorption rate on the release of lead from bone in 333 men, predominantly white, middle-aged and elderly (mostly retired) from the Boston area. We evaluated bone resorption by measuring cross-linked N-telopeptides of type I collagen (NTx) in 24-hr urine samples with an enzyme-linked immunosorbent assay. We used K-X-ray fluorescence to measure lead content in cortical (tibia) and trabecular (patella) bone; we used graphite furnace atomic absorption spectroscopy and inductively coupled plasma mass spectroscopy to measure lead in blood and urine, respectively. After adjustment for age and creatinine clearance, the positive relation of patella lead to urinary lead was stronger among subjects in the upper two NTx tertiles (beta for patella lead > or =0.015) than in the lowest NTx tertile (beta for patella lead = 0.008; overall p-value for interactions = 0.06). In contrast, we found no statistically significant influence of NTx tertile on the relationship of blood lead to urinary lead. As expected, the magnitude of the relationship of bone lead to urinary lead diminished after adjustment for blood lead. Nevertheless, the pattern of the relationships of bone lead to urinary lead across NTx tertiles remained unchanged. Furthermore, after adjustment for age, the relation of patella lead to blood lead was significantly stronger in the upper two NTx tertiles (beta for patella lead > or =0.125) than in the lowest NTx tertile (beta for patella lead = 0.072). The results provide evidence that bone resorption influences the release of bone lead stores (particularly patella lead) into the circulation.

Adult↗

PubMed1998

Determination of the total arsenic concentration in human urine by inductively coupled plasma mass spectrometry: a comparison of the accuracy of three analytical methods.

Measurement of arsenic (As) in biological samples such as urine has important clinical applications and is being undertaken more frequently in epidemiologic studies because of concern about the carcinogenicity of low to moderate levels of As exposure. The objective of this study was to evaluate and improve the accuracy of As determination in urine by inductively coupled plasma mass spectrometry (ICP-MS). Determination of As in biological samples by ICP-MS is difficult for two reasons: the formation of the molecular ion 40Ar35Cl, which overlaps with monoisotopic As at a mass-to-charge ratio (m/z) of 75 (causing spectral interference), and signal enhancement due to organic matrix (nonspectral interference). Available procedures were examined, including the application of different correction procedures using 40Ar37Cl and 16O35Cl molecular-ion formation; the addition of N2 into plasma or nebulizer gas flows; and the addition of organic molecules to the sample and to calibration standards to eliminate or correct for interference due to molecular-ion formation. The accuracy and precision of determination of As [m/z 75, ionization potential (IP) 9.81 eV] with use of an internal standard was also investigated. Three elements were studied as candidate internal standards: germanium (Ge: m/z 74, IP 7.90 eV), indium (In: m/z 115, IP 5.79 eV), and tellurium (Te: m/z 128, IP 9.01 eV). It was found that these three elements performed more or less equally well with Ar-N2 plasma; it was also found that accuracy was significantly improved when Te was used as the internal standard instead of Ge or In for ethanol-added samples. Our results indicate that accurate and precise measurement of As in urine by ICP-MS can be obtained by either of two methods (< 5% error, approximately 2% RSD, limit of detection 0.1 ng ml-1): (1) the addition of 1% N2 to plasma gas flow or 3% N2 to nebulizer gas flow, along with use of any of the internal standards tested, or (2) the addition of ethanol to the sample and to calibration standards, with use of Te as the internal standard. The most accurate results (< 1% error) for National Institute of Standard and Technology Standard Reference Material (NIST SRM) 2670 (toxic elements in urine) were obtained with Ar-N2 plasma with either Te or In as the internal standard.

Arsenic↗

PubMed1996

Determinants of bone and blood lead levels among community-exposed middle-aged to elderly men. The normative aging study.

Levels of lead in bone serve as a dosimeter for cumulative exposure to lead; moreover, lead in bone may serve as an internal source of circulating lead many years after environmental exposure has ceased. The authors measured lead in blood and used a K-x-ray fluorescence instrument to measure lead in the tibia (cortical) and patella (trabecular) bones in a cross-sectional survey of 719 middle-aged to elderly male participants in the Normative Aging Study who were without unusual occupational exposures to lead and who were healthy when enrolled in 1962-1965. Blood lead levels ranged from < 1 to 27.9 micrograms/dl, with a geometric mean of 5.7 micrograms/dl. Tibia and patella lead level ranges (geometric means) were < 1-51 (20.8) micrograms/g and 3-77 (29.8) micrograms/g, respectively. In backwards elimination multivariate regression models that considered age, race, education, retirement status, measures of both current and cumulative smoking, and alcohol consumption, the factors that remained significantly related to higher levels of both tibia and patella lead were higher age and measures of cumulative smoking, and lower levels of education. In the final model predicting blood lead that began with these same covariates and also included tibia and patella lead, the factor that accounted for the dominant portion of the variance in blood lead was patella lead. After adjustment for measurement error, a rise in patella lead from the median of the lowest to the median of the highest quintiles (13-56 micrograms/g) corresponded to a rise in blood lead of 4.3 micrograms/dl. The authors conclude that bone lead levels are substantial and comprise the major source of circulating lead in these men.

Adult↗

PubMed1996

The relationship of bone and blood lead to hypertension. The Normative Aging Study.

OBJECTIVE: To test the hypothesis that long-term lead accumulation, as reflected by levels of lead in bone (as opposed to blood which reflects recent lead exposure), is associated with an increased odds of developing hypertension. DESIGN: Case-control study of participants in the Veterans Administration (now Department of Veterans Affairs) Normative Aging Study, a 30-year longitudinal study of men. PARTICIPANTS: Of 1171 active subjects who were seen between August 1991 and December 1994, 590 (50%) participated in this investigation and had data on all variables of interest. MAIN OUTCOME MEASURES: Hypertension was defined as taking daily medication for the treatment of hypertension or systolic blood pressure higher than 160 mm Hg or diastolic blood pressure of 96 mm Hg or higher during the time of examination. Levels of lead in the tibia (representing cortical bone) and the patella (representing trabecular bone) were measured in vivo with a K x-ray fluorescence (KXRF) instrument. Levels of lead in blood were measured by graphite furnace atomic absorption spectroscopy. RESULTS: Blood lead levels were low, ranging from less than 0.05 to 1.35 micromol/L (<1 to 28 microgram/dL), with a mean (SD) of 0.30 (0.20) micromol/L (6.3[4.1] microgram/dL). Bone lead levels were similar to those described in other general populations. In comparison to nonhypertensives, mean levels of lead in blood and both tibia and patella bone lead levels were significantly higher in hypertensive subjects. In a logistic regression model of hypertensive status that began with age, race, body mass index, family history of hypertension, history of ethanol ingestion, pack-years of smoking, dietary sodium intake, dietary calcium intake, blood lead, tibia lead, and patella lead, the variables that remained after backward elimination were body mass index, family history of hypertension, and level of lead in the tibia. An increase from the midpoint of the lowest quintile to the midpoint of the highest quintile of tibia lead from 3 to 37 micrograms per gram of bone mineral was associated with an increased odds ratio of hypertension of 1.5. CONCLUSION: Our findings suggest that long-term lead accumulation, as reflected by levels of lead in bone, may be an independent risk factor for developing hypertension in men in the general population.

Age Factors↗

PubMed1994

The relationship between bone lead and hemoglobin.

OBJECTIVE: To determine whether the concentration of lead in bone constitutes a biological marker that is more sensitive for chronic toxicity than blood lead levels. DESIGN: Survey. SETTING: A construction trade union with members who engage in carpentry, demolition, and other construction activities. PARTICIPANTS: Members of the construction trade union. MAIN OUTCOME MEASURES: We measured blood pressure, serum creatinine, hematocrit, and hemoglobin. We measured blood lead by anodic stripping voltametry and used a cadmium 109 K x-ray fluorescence instrument to make in vivo measurements of lead in the tibia (a heavily cortical bone) and the patella (a heavily trabecular bone). Information was also collected on medical history, smoking, and alcohol ingestion. RESULTS: Bone lead levels in the patella were found to be significantly correlated with a decrease in hemoglobin and hematocrit, even after adjusting for age, blood lead, body mass index, cigarette smoking, and alcohol ingestion and removing outliers. Blood lead levels were low (mean = 0.40 mumol/L [8.3 micrograms/dL]) and were not correlated with either hemoglobin or hematocrit. In the final multivariate regression model that corrected for measurement error, an increase in patella bone lead level from the lowest to highest quintile in this study population (37 micrograms/g) was associated with a decrease in hemoglobin and hematocrit of 11 g/L (95% confidence interval [CI], 2.7 to 19.3 g/L) and 0.03 (95% CI, 0.01 to 0.05), respectively. CONCLUSION: We conclude that patella bone lead levels are associated with decreased hematocrit and hemoglobin levels despite the presence of low blood lead levels. This conclusion may reflect a subclinical effect of bone lead stores on hematopoiesis and is the first epidemiological evidence that bone lead may be an important biological marker of ongoing chronic toxicity.

Adult↗